FIG. 3.

A 36-amino-acid region of TBP is sufficient for specific interaction with T antigen. (A) Purified full-length T antigen (TAg; 0.5 μg) was incubated with 10 μl of glutathione-agarose containing GST or the indicated GST-TBP fusion proteins in the presence of 1 U of benzonase (lanes 2 to 5, 7 to 10, and 12 to 16). After the beads were washed, the proteins were eluted by boiling in sample buffer and separated by SDS-PAGE (10% polyacrylamide gel). Bound T antigen was detected by immunoblotting using the monoclonal anti-T-antigen antibody Pab419. As a control, 0.1 μg of the input T antigen was analyzed in parallel (lanes 1, 6, and 11). (B) The beads containing the GST fusion proteins used for panel A (10 μl) were analyzed by SDS-PAGE (12.5% polyacrylamide gel) and staining with Coomassie brilliant blue. PM, prestained marker proteins; M, protein molecular weight markers.